abhi01
Forum Newbie
Topics: 6
Posts: 18
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survival rates after surgery
N 1yr 2yr 3yr 4yr
183 90% 75% 50% 40%
if the patient survives for 2 yrs, what is the chance of this patient surviving for one more yr.
hi guys i am not sure how to approach this question. are the two events non independent of each other and not mutually exclusive.
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| p53
Forum Guru
Topics: 51
Posts: 804
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let's say that in the beginning there were 100 pateints. after 1 year 90 were left, after 2 years - 75. this number - 75 - is now 100% for us. after 3 years only 50 patients were left - chances for each patient who survived 2 years to survive 1 more year are 50/75, i.e. 2 out of 3, i.e. 66%.
you don't need 183.
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| achilles
Forum Guru
Topics: 87
Posts: 1,212
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thats right...at the end of 3 yrs there will be 50 people surviving. and at the end of 2 yrs there are 75 people who have survived. so the chance that he will survive one more year is 50/75=66%
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| frank100
Forum Guru
Topics: 48
Posts: 586
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cool
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